Diabetes mellitus (DM) is impaired insulin secretion and variable degrees of peripheral insulin resistance leading to hyperglycemia.
Years of poorly controlled hyperglycemia lead to multiple, primarily vascular complications that affect small vessels (microvascular), large vessels (macrovascular), or both. Indeed, diabetes mellitus is one of the major causes of premature morbidity and mortality.
The mechanisms by which vascular disease develops include glycosylation of serum and tissue proteins with formation of advanced glycation end products; superoxide production; activation of protein kinase C, a signalling molecule that increases vascular permeability and causes endothelial dysfunction; accelerated hexosamine biosynthetic and polyol pathways leading to sorbitol accumulation within tissues; hypertension and dyslipidemia that commonly accompany DM; arterial microthromboses; and proinflammatory and prothrombotic effects of hyperglycemia and hyperinsulinemia that impair vascular autoregulation. Immune dysfunction is another major complication and develops from the direct effects of hyperglycemia on cellular immunity.
Effective control of blood/plasma glucose can prevent or delay many of these complications but may not reverse them once established. Hence, achieving good glycemic control in efforts to prevent diabetes complications is the primary goal in the treatment of type 1 and type 2 diabetes.
Studies also support the role of glycated haemoglobin (HbA1c) reduction in decreasing cardiovascular disease risk (Nathan D M, Cleary P A, Backlund J Y, et al. Intensive diabetes treatment and cardiovascular disease in patients with type 1 diabetes. N Engl J Med 2005; 353:2643-53; Selvin E, Marinopoulos S, Berkenblit G, et al. Meta-analysis: glycosylated hemoglobin and cardiovascular disease in diabetes mellitus. Ann Intern Med 2004; 141:421-31). The general goal of an HbA1c level of below 7% has been recommended by many diabetes organisations (e.g., the American Diabetes Association (ADA)). In the UKPDS, 50% of patients were taking insulin therapy to maintain HbA1c levels of below 7% within 6 years of the diagnosis of type 2 diabetes.
There are numerous non-insulin treatment options for diabetes, however, as the disease progresses, the most robust response will usually be with insulin. Indeed, since diabetes is associated with progressive β-cell loss, many patients, especially those with long-standing disease, will eventually need to be transitioned to insulin, since the degree of hyperglycemia (e.g., HbA1c≥8.5%) makes it unlikely that another drug will be of sufficient benefit.
Most patients express reluctance to beginning injectable therapy, due to discomfort and inconvenience caused by the high demands for blood glucose testing and insulin injection. Traditionally, the use of insulin to improve glycaemic control was provided by medical specialists. With the increasing number of patients under primary care for whom insulin is indicated, prescribing it in the same setting appears much more convenient for the end users. Often however, insulin is not started in time, due to psychological resistance from both doctors and patients.
A consensus statement from the American Diabetes Association (ADA) and the European Association for the Study of Diabetes (EASD) was updated in 2012, and emphasised a patient-centred approach and individualised HbA1c treatment targets for the management of hyperglycaemia in type 2 diabetes (T2DM). It recommended that insulin could be considered as one of the options for dual combination therapy, if an individualised HbA1c level target was not reached after metformin therapy. This choice could be based on patient and drug characteristics, with an over-riding goal of improving glycaemic control while minimising side-effects. When three-drug combinations are considered, insulin is likely to be more effective than most other agents (e.g., sulfonylurea, thiazolidinedione, dipeptidyl peptidase 4 inhibitor, glucagon-like peptide-1 receptor agonist), especially when the HbA1c level is very high (≥9.0%) (Inzucchi S E, Bergenstal R M, Buse J B, et al., Management of hyperglycemia in type 2 diabetes: a patient-centered approach: position statement of the American Diabetes Association (ADA) and the European Association for the Study of Diabetes (EASD). Diabetes Care 2012; 35:1364-79).
The ideal insulin regimen aims to mimic the physiological profile of insulin secretion as closely as possible. There are two major components in the insulin profile: a continuous basal secretion and prandial surge after meals. The basal secretion controls overnight and fasting glucose while the prandial surges control postprandial hyperglycaemia.
Based on the time of onset and duration of their actions, injectable formulations can be broadly divided into basal (long-acting analogues [e.g., insulin detemir and insulin glargine] and ultra-long-acting analogues [e.g., insulin degludec]) and intermediate-acting insulin [e.g., isophane insulin] and prandial (rapid-acting analogues [e.g., insulin aspart, insulin glulisine and insulin lispro]). Premixed insulin formulations incorporate both basal and prandial insulin components.
There are various recommended insulin regimes, such as (1) multiple injection regimen: rapid-acting insulin before meals with long-acting insulin once or twice daily; (2) premixed analogues or human premixed insulin once or twice daily before meals; (3) intermediate- or long-acting insulin once or twice daily. However, where possible, a long-acting insulin regimen alone or in combination with oral antidiabetic drug(s) (OADs) is usually the optimal initial regimen for subjects with T2DM as this reduces the patient burden and discomfort caused by blood glucose measurement and injection of insulin.
Recent data from the United Kingdom Prospective Diabetes Study suggest the importance of stringent glycaemic control (Holman R R, Paul S K, Bethel M A, Matthews D R, Neil H A. 10-year follow-up of intensive glucose control in type 2 diabetes. N Engl J Med 2008; 359: 1577-1589) and current treatment guidelines call for early insulin treatment in type 2 diabetes patients (Nathan D M, Buse J B, Davidson M B et al. Management of hyperglycemia in type 2 diabetes: a consensus algorithm for the initiation and adjustment of therapy: update regarding thiazolidinediones: a consensus statement from the American Diabetes Association and the European Association for the Study of Diabetes. Diabetes Care 2008; 31: 173-175). However, optimal initiation and titration methods for the long-acting basal insulins are still being determined. Evidence suggests that many patients often do not have insulin doses titrated sufficiently to achieve target levels of glucose control (remaining on suboptimal doses and failing to reach treatment targets) (UK Prospective Diabetes Study (UKPDS) Group).
What has become increasingly clear is that patient empowerment is essential for motivation to reach treatment targets. Self-titration regimens facilitate empowerment of patients, allowing them to become more involved in their treatment, which can result in improved glycaemic control. Until recently, titration of insulin in type 2 diabetes clinical trials was typically left up to the investigator's discretion with a simple statement of the target ranges for glucose. In type 2 diabetes trials the average glycemic control achieved was usually less than desirable. Since then a number of trials have been conducted and reported utilizing various algorithms under various conditions.
During the last decade various insulin titration algorithms have been applied in several trials initiating long or intermediate acting insulin in type 2 diabetes patients often referred to as Treat-to-target. Several of the trials were designed for other primary purposes than algorithm development and have therefore used one specific algorithm. Interpretation of algorithm merit in those cases is somewhat difficult and has to rely on cross trial comparisons. Various factors in addition to the numbers in the algorithm apparently affect the achieved results.
The algorithms for basal insulin titration and their implementation have evolved steadily further away from complete real time health care provider control over every dose decision. The first step was the acceptance of one algorithm for all patients, which at the time was considered radical by most investigators. The second step became acceptance algorithm enforcement.
Controlled clinical trials such as the Diabetes Control and Complications Trial (The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. The Diabetes Control and Complications Trial Research Group. N Engl J Med 1993; 329:977-86), the UK Prospective Diabetes Study (UKPDS) (Intensive blood-glucose control with sulphonylureas or insulin compared with conventional treatment and risk of complications in patients with type 2 diabetes (UKPDS 33), UK Prospective Diabetes Study (UKPDS) Group. Lancet 1998; 352:837-53), the Veterans Affairs Diabetes Trial (Duckworth W, Abraira C, Moritz T, et al. Glucose control and vascular complications in veterans with type 2 diabetes. N Engl J Med 2009; 360:129-39), the Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation trial (ADVANCE Collaborative Group, Patel A, MacMahon S, et al. Intensive blood glucose control and vascular outcomes in patients with type 2 diabetes. N Engl J Med 2008; 358:2560-72), and a study on Japanese patients (Ohkubo Y, Kishikawa H, Araki E, et al. Intensive insulin therapy prevents the progression of diabetic microvascular complications in Japanese patients with non-insulin-dependent diabetes mellitus: a randomized prospective 6-year study. Diabetes Res Clin Pract 1995; 28:103-17) demonstrated that intensive glycaemic control could significantly reduce the risk of microvascular complications.
Common to all basal insulin titration algorithms is that dose changes are based on averages of a varying number of days' morning fasting self-monitored blood or plasma glucose. From this general theme there are many variations.
The starting dose has been 10 U, 20 U, or based on the morning fasting plasma glucose (FPG) using the formula of Holman and Turner (Holman R R, Turner R C. A practical guide to basal and prandial insulin therapy. Diabet Med. 1985 January; 2(1):45-53) which is (FPG (mg/dl)−50)/10, typically yielding just short of 20 U. Within these options there does not appear to be any difference in achieved glycemic control and hypoglycemia rate.
When a clinic has to titrate the insulin dose for the individual patient, there is often a natural limitation on the possible frequency. Consequently, the clinic has to be able to make substantial dose increments at high average glucose so the patient is not left for too long a time in poor glycemic control. However, the patient can easily titrate often, for which there is a long tradition for those with type 1 diabetes. With more frequent titration there may be a reduced need for large dose steps at high glucose levels and the algorithms can be simplified in terms of number of steps.
Earlier titration protocols typically titrated an insulin dose based on the average of a week's worth of several fasting blood/plasma measurements. Later trials are based on dose titrations based on average fasting blood/plasma measurements based of 3 measurements per week.
At the extreme is INSIGHT (Gerstein H C, Yale J F, Harris S B, Issa M, Stewart J A, Dempsey E. A randomized trial of adding insulin glargine vs. avoidance of insulin in people with Type 2 diabetes on either no oral glucose-lowering agents or submaximal doses of metformin and/or sulphonylureas. The Canadian INSIGHT (Implementing New Strategies with Insulin Glargine for Hyperglycaemia Treatment) Study. Diabet Med. 2006 July; 23(7):736-42), which has only one step of one unit of insulin titrated every morning by the patient.
Clinic contact initially occurred every other week, but after 4 weeks the clinic contact went to every 4 weeks and after 12 weeks to 6-week intervals. Clinic oversight was thus minimally if at all intensified compared to standard clinical practice. Patients were taught to “start with an initial dose of 10 units, and advised to increase this by 1 unit each day until achieving a FPG (FPG)≤5.5 mmol/liter (99 mg/dl).” The end insulin dose was 38 U and HbA1c 7.0%. From an effectiveness point of view, this is an “outstanding” result. Hence, there is a trend toward increasingly high frequency of insulin dose titration in order to improve to primary aim of insulin therapy—glycaemic control.
Diabetes care guidelines and product labelling for current basal insulin analogs recommend regular blood glucose self-measurement (American Diabetes Association. Standards of Medical Care in Diabetes—2012. Diabetes Care. 2012; 35(Suppl 1):S11-63; International Diabetes Federation Clinical Guidelines Task Force. Global Guideline for Type 2 Diabetes. 2005. Available at: http://www.idf.org/webdata/docs/IDF%20GGT2D.pdf. Accessed Dec. 19, 2012; Canadian Diabetes Association Clinical Practice Guidelines Expert Committee. Canadian Diabetes Association. Can J Diabetes. 2008; 32(Suppl 1):S1-201; Meneghini L, Koenen C, Wenig W, Selam J-L. The usage of a simplified self-titration dosing guideline (303 Algorithm) for insulin detemir in patients with type 2 diabetes results of the randomized, controlled PREDICTIVE™ 303 study. Diabetes Obes Metab. 2007; 9:902-13; Davies M, Storms F, Shutler S, Bianchi-Biscay M, Gomis R. Improvement of glycemic control in subjects with poorly controlled type 2 diabetes. Diabetes Care. 2005; 28:1282-8; and LANTUS® (insulin glargine [rDNA origin] injection). Sanofi-aventis U.S. LLC, Bridgewater, N.J., USA; 2007. Health Care Professional. Dosing & Titration. Available at: http://www.lantus.com/hcp/titration.aspx. Accessed Nov. 13, 2012) in order to help people with diabetes maintain appropriate glycemic control and become more actively involved in their healthcare (Benjamin E M. Self-monitoring of blood glucose: the basics. Clin Diabetes. 2002; 20(1):45-7; Schnell O, Saarlouis H A, Battelino T B, et al. Consensus statement on self-monitoring of blood glucose in diabetes. Diabetes, Stoffwechsel and Herz. 2009; 4:285-9; and American Diabetes Association. Insulin administration. Diabetes Care. 2012; 35:S1). Insulin dose is also typically determined and titrated up or down as needed according to algorithms based on blood glucose results (American Diabetes Association. Standards of Medical Care in Diabetes—2014. Diabetes Care. 2014; 37 Suppl 1). Insulin dose determination is individual for each patient. The dose steps (titration model), the glycemic target as well as the absolute insulin dose are determined in an individualised and tailored manner for each individual generally by a healthcare provider (HCP).
Challenges exist that can prevent the achievement of glycemic targets with insulin, including perceptions on the part of patients and HCPs that insulin therapy can be burdensome or too complex to manage (Peyrot M, Barnett A H, Meneghini L F, Schumm-Draeger P M. Factors associated with injection omission/non-adherence in the Global Attitudes of Patients and Physicians in Insulin Therapy Study. Diabetes Obes Metab. 2012; 14:1081-7; and Peyrot M, Barnett A H, Meneghini L F, Schumm-Draeger P M. Insulin adherence behaviours and barriers in the multinational Global Attitudes of Patients and Physicians in insulin therapy study. Diabet Med. 2012; 29:682-90). Patients who take an active role in the management of their diabetes and titration of their insulin may feel more empowered to take charge of their self-care and have a stronger belief that their actions can influence their disease, thus leading to better treatment outcomes (Norris S L, Lau J, Smith S J, et al. Self-management education for adults with type 2 diabetes: a meta-analysis on the effect of glycemic control. Diabetes Care. 2002; 25:1159-71; Kulzer B, Hermanns N, Reinecker H, Haak T. Effects of self-management training in type 2 diabetes: a randomized, prospective trial. Diabet Med. 2007; 24:415-23; Anderson R M, Funnell M M, Butler P M, et al. Patient empowerment: results of a randomized controlled trial. Diabetes Care. 1995; 18:943-9). In determining how self-care can best be facilitated for patients with diabetes, the cost and burden of frequent glucose testing must be considered when designing treatment plans, as these can be significant factors when added to the health, quality of life (QoL), and financial toll of poorly controlled diabetes.
Numerous studies investigating the cost of self-measured blood glucose (SMBG) testing have found that it comprises a substantial portion of diabetes-related expenditures (Liebl A, Breitscheidel L, Nicolay C, Happich M. Direct costs and health-related resource utilisation in the 6 months after insulin initiation in German patients with type 2 diabetes mellitus in 2006: INSTIGATE study. Curr Med Res Opin. 2008; 24:2349-58; Yeaw J, Christensen T E, Groleau D, Wolden M L, Lee W C. Self-monitoring blood glucose test strip utilization in Canada. Diabetes. 2012; 61(Suppl 1):A35; Yeaw J, Lee W C, Wolden M L, Christensen T, Groleau D. Cost of self-monitoring of blood glucose in Canada among patients on an insulin regimen for diabetes. Diabetes Ther. Epub Jun. 27, 2012. doi: 10.1007/s13300-012-0007-6; and Yeaw J, Lee W C, Aagren M, Christensen T J. Cost of self-monitoring of blood glucose in the United States among patients on an insulin regimen for diabetes. J Manag Care Pharm. 2012; 18:21-32). In a retrospective database analysis in the US that included more than 45,000 patients, testing accounted for 27% of diabetes care costs: total combined blood glucose testing and insulin-related costs were $2,850 USD/patient/year, with $772 USD/patient/year attributed to blood glucose testing alone (Yeaw J, Lee W C, Aagren M, Christensen T J. Cost of self-monitoring of blood glucose in the United States among patients on an insulin regimen for diabetes. J Manag Care Pharm. 2012; 18:21-32). In other countries, testing comprises an even higher percentage of diabetes care costs, e.g., 40% in Canada (Yeaw J, Christensen T E, Groleau D, Wolden M L, Lee W C. Self-monitoring blood glucose test strip utilization in Canada. Diabetes. 2012; 61(Suppl 1):A35; Yeaw J, Lee W C, Wolden M L, Christensen T, Groleau D. Cost of self-monitoring of blood glucose in Canada among patients on an insulin regimen for diabetes. Diabetes Ther. Epub Jun. 27, 2012. doi: 10.1007/s13300-012-0007-6) and 42% in Germany (Liebl A, Breitscheidel L, Nicolay C, Happich M. Direct costs and health-related resource utilisation in the 6 months after insulin initiation in German patients with type 2 diabetes mellitus in 2006: INSTIGATE study. Curr Med Res Opin. 2008; 24:2349-58).
Hence, there is pressure to reduce the frequency of blood glucose measurement in order to improve patient quality of life, improve administration regime adherence (leading to improved patient outcomes) and reduce treatment costs. However, there are conflicting pressures to increase the frequency of blood glucose measurement and insulin administration in order to most effectively achieve glycemic control and thereby reduce diabetes-associated complications.
Accordingly, there is an ongoing need to provide improved approaches for long- and ultra-long-acting insulin dosing and administration.